Wheel support for vehicles with disk brakes

ABSTRACT

A wheel support for providing a connection, rotatable about an axis (S), between a wheel of a vehicle which can be braked by a disk brake and the stub axle ( 6 ) of the vehicle comprises a bell ( 24 ) suitable for supporting a braking band ( 25 ) and a connection flange ( 14 ) for the connection of the vehicle wheel. The bell ( 24 ) and the connection flange ( 14 ) are formed integrally, constituting a single body ( 2 ) which can be connected rotatably and releasably to the stub axle ( 6 ) of the vehicle.

BACKGROUND OF THE INVENTION

[0001] The subject of the present invention is a wheel support forproviding a rotatable connection between a wheel and suspension means ofa vehicle with disk brakes, in particular a heavy vehicle the wheelflange of which has an outside diameter larger than the inside diameterof the brake disk used.

[0002] In these vehicles, a worn brake disk is generally replaced bydismantling the wheel-bearing unit.

[0003] However, the life of the bearings, which is generally longer thanthat of the brake disks, is guaranteed by producers only if the bearingsare never dismantled after their initial assembly.

[0004] There is therefore a need to provide braking systems which enablethe brake disk to be replaced without dismantling the bearing unit.

[0005] Solutions have been proposed to fulfil this need but, althoughthey avoid dismantling the bearing, they have other disadvantages. Forexample, there are known disk brakes with braking bands which aredivided into two parts connected to one another releasably to enablethem to be replaced without the need to remove the bearing unit from thestub axle.

[0006] The main disadvantage of this solution is that it is difficult toensure precise alignment between the two portions of the braking band,particularly in an axial direction, because of working tolerances bothof the two parts of the braking band and of the connection between them.

[0007] As a result, the braking surfaces of the two assembled parts donot define a single braking surface and a stepped discontinuity isformed along the line of the joint between the two parts of the brakingband. During braking, this step acts as a tool which removes frictionmaterial from the braking surfaces of the pads, causing rapid and unevenwear of the pads.

[0008] A further system of the prior art comprises a bearing, a brakedisk, and a wheel hub, which are independent of one another and whichcan be connected by a set of screws, the screws being inserted insuitable holes provided in the wheel hub and in the bell of the brakedisk and screwed into threaded holes in the outer ring of the bearing,clamping the bell of the brake disk between the wheel hub and thebearing, as can be seen in FIG. 2.

[0009] Although this solution does not require operation on the bearingduring the replacement of the worn brake disk, it has the disadvantageof the presence of a fairly large bell which cannot be reused after thereplacement of the disk.

[0010] Moreover, in this solution it is necessary to provide for twocentring arrangements, that is, centring of the disk on the bearing andcentring of the wheel hub on the disk bell, requiring at least fourmachining operations which are difficult and expensive to perform.

[0011] Furthermore, any use of axially slidable braking bands isrendered difficult and expensive by the large number of parts to beproduced and assembled.

[0012] With regard to the structural behaviour of the systems of theprior art, they have highly stressed connection members such as the pinsand the bolts which connect the two sectional portions of the brakedisk, as well as the screws for connecting the wheel hub and thebrake-disk bell to the bearing. In particular, during braking, thelatter have to ensure that the joint they form can transmit the brakingtorque from the brake-disk bell to the wheel flange.

SUMMARY OF THE INVENTION

[0013] The object of the present invention is therefore to propose awheel support for vehicles of the type specified above which enablesworn parts of the braking system to be replaced without the need toperform operations on the bearing, at the same time overcoming thedisadvantages of the prior art.

[0014] Within the object of the invention set out above, a further aimis to provide a wheel support having characteristics such as to stressthe principal connection members uniformly and such as to favour easyand safe replacement of the brake disk.

[0015] These and other objects are achieved by means of a wheel supportaccording to claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] For a better understanding of the invention, a non-limitingembodiment thereof is described below and is shown in the appendeddrawings, in which:

[0017]FIG. 1 is a sectioned, perspective view of a wheel-support unitaccording to the invention,

[0018]FIG. 2 is a view showing a wheel-support unit of the prior art, insection,

[0019]FIG. 3 is an exploded view of the wheel-support unit of FIG. 1,

[0020]FIG. 4 is a further exploded view of the wheel-support unit ofFIG. 1,

[0021]FIG. 5 shows, in section, the wheel-support unit of FIG. 1, afterthe removal of a component thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] With reference to FIGS. 1, 3 and 4, a wheel-support unit isgenerally indicated 1. The wheel-support unit comprises a connectionflange 14, a bell 24, and a bearing 3, the connection flange 14 and thebell 24 being formed integrally so as to constitute a single body 2.

[0023] The terms “axial” and “radial” refer below to the axis ofrotation of the individual components (the brake disk, the wheel, theouter ring of the bearing) when they are mounted on the vehicle. Thisrotation axis coincides substantially with the axis S of symmetry or ofaxial symmetry of the above-mentioned components, as specified below.The expressions “interior of the vehicle” and “exterior of the vehicle”,on the other hand, relate to the orientation of the components when theyare mounted on the vehicle.

[0024] The single body 2 has a geometrical shape which is substantiallythat of an axially symmetrical body of revolution, comprising a tubularportion 13 facing towards the interior of the vehicle, as well as asubstantially annular disk-shaped connection flange 14 perpendicular tothe axis S. The connection flange 14 is formed on the end of the singlebody 2 remote from the tubular portion 13 and has a plurality of axialthrough-holes 15 distributed at intervals around a circle having itscentre on the axis S. In known manner, the axial holes 15 house, withinterference, a corresponding plurality of bolts, known as “studs”,provided for the screwing of a plurality of nuts for the releasableconnection of a wheel to the connection flange 14.

[0025] A substantially frustoconical connecting region 16 is formedbetween the tubular portion 13 and the connection flange 14 and isfurther reinforced by reinforcing ribs 17.

[0026] The tubular portion 13 of the single body 2 has an outer surface18 and an inner surface 19. The inner surface 19 defines a substantiallycylindrical seat 20 which can be fitted, along the axis S, onto aconnecting portion 8 of the bearing 3, in order to house the connectingportion 8 at least partially but preferably completely.

[0027] As can be seen, for example, from FIG. 1, the seat 20 has acentring portion of limited depth the inside diameter of whichcorresponds substantially to the outside diameter of the connectingportion 8 of the bearing 3. The total depth of the seat 20 is greaterthan the axial length of the connecting portion 8.

[0028] The seat 20 is defined, in the axial direction, by a shoulder 21with a flat abutment surface 22 substantially perpendicular to the axisS and facing towards the interior of the vehicle. The abutment surface22 is at least partially complementary with a front surface 10 of thebearing 3.

[0029] The shoulder 21 has a plurality of axial through-holes 23 whichopen in the abutment surface 22. The holes 23 are distributed so as tobe aligned with threaded holes 11 in the front surface 10 of the bearing3 and can house a plurality of bolts 12 for releasable connection to thebearing 3.

[0030] According to one embodiment, the holes 23 are distributed atintervals around a circle having its centre on the axis S.

[0031] The outer surface of the tubular portion 13 of the single body 2forms a bell region 24 for the releasable connection of a braking band25 to the single body 2, fixing them for rotation together about theaxis S. This releasable connection between the braking band 25 and thesingle body 2 takes place in known manner and only one of the possibleconnection methods will therefore be described below.

[0032] With reference to FIGS. 3 and 4, a plurality of projections,parallel to one another and to the axis S, are formed in the bell region24 and project substantially radially, forming a set of teeth 26. Theset of teeth 26 has an inner abutment surface 28 facing towards theinterior of the vehicle and an outer abutment surface 30, facing towardsthe exterior of the vehicle.

[0033] The set of teeth 26 of the bell region 24 is intended to engage acorresponding set of teeth 27 formed around the circumference of thecentral opening of the braking band 25 and in turn provided withinternal and external abutment surfaces 29 and 31, respectively.

[0034] According to one embodiment, the bell region 24 for thereleasable connection of the braking band 25 to the single body 2 isdisposed substantially centrally relative to the axial extent of thebearing 3.

[0035] The bearing 3 has an inner ring 4 which can be keyed to a stubaxle 6 of a vehicle and an outer ring 5, associated rotatably with theinner ring 4, for example, by means of conical rollers housed insuitable rolling races between the two rings 4 and 5.

[0036] The bearing 3 as a whole is shaped geometrically substantially asan axially symmetrical body of revolution in which the outer ring 5 hasa first tubular portion 7 and a second tubular portion which is enlargedradially relative to the first portion 7 and which constitutes theconnecting portion 8. A substantially frustoconical transition region 9is formed between the first tubular portion 7 and the connecting portion8.

[0037] The connecting portion 8 comprises a flat front surface 10substantially perpendicular to the axis S. The front surface 10 facestowards the exterior of the vehicle and is at least partiallycomplementary with the abutment surface 22 of the single body 2.

[0038] A plurality of axial holes 11 formed in the front surface 10 arealigned with the through-holes 23 provided in the abutment surface 22 ofthe single body 2. The holes 11, which are threaded internally, aredistributed at intervals around a circle having its centre on the axis Sand are provided for the screwing of the plurality of bolts 12 for thereleasable connection of the single body 2 to the connecting portion 8of the bearing 3. The radial enlargement of the connecting portion 8corresponds substantially to the space required to house the bolts 12.

[0039] According to the preferred embodiment, the bearing 3 is made ofsteel, the single body 2 of nodular cast iron, and the braking band ofgrey iron.

[0040] The operation of the wheel-support unit 1 for vehicles with diskbrakes is described below with reference to FIGS. 4 and 5.

[0041] For the initial mounting, the bearing 3, the single body 2, andthe braking band 25 are arranged to be preassembled to form a singleunit which is mounted on the stub axle 6 prior to the mounting of thecaliper.

[0042] The bearing 3 is never opened again, throughout its entire life,guaranteed by the manufacturers.

[0043] The wheel is connected to the single body 2, in known manner, bymeans of a plurality of nuts which are screwed onto the studs of theconnection flange 14.

[0044] During braking, the braking torque is transmitted by the sets ofteeth 26 and 27 from the braking band 25 to the single body 2, and hencedirectly to the connection flange 14, without requiring any furtherstressing of the bolts 12 which connect the single body 2 to the bearing3. The braking torque is transmitted from the single body 2 to the wheelby the joint formed by the wheel-mounting studs.

[0045] A worn braking band is replaced, after the wheel has been removedfrom the single body 2 by unscrewing of the screws 34 which restrain thebraking band 25 axially in the bell region 24. The screws 34 can bereached easily from outside the vehicle, as can be seen, for example,from FIG. 1 or FIG. 3.

[0046] The bolts 12 are then unscrewed from the connecting portion 8,releasing the single body 2, which can easily be removed by being slidalong the axis S.

[0047] Since the central opening in the braking band 25 has a diameterlarger than the outside diameter of the bearing 3, it allows the wornbraking band to be removed and replaced without any operation on thebearing 3. The individual pieces 33 a, 33 b of a keeper ring 33 caneasily be separated from the tubular portion 13 of the single body 2 andcan be re-used.

[0048] After the new braking band 25 has been positioned between thepads of the caliper by being supported, for example, directly on theouter ring 5 of the bearing 3, the single body 2 is put in place byfitting the seat 20 onto the connecting portion 8 of the bearing 3,along the axis S.

[0049] The substantially complementary shapes of the centring portion ofthe seat 20 and of the connecting portion 8 advantageously facilitatethe locating of the single body 2, which is fixed by the screwing of thebolts 12 into the threaded holes 11 in the front surface 10 of thebearing 3.

[0050] During or after the positioning of the single body 2 on thebearing 3, the tubular portion 13 is inserted, again along the axis S,in the central opening of the braking band 25 in which the first set ofteeth 26 in the bell region 24 engage the second set of teeth 27 of thebraking band 25, achieving a form coupling which prevents their relativerotation about the axis S.

[0051] The braking band 25 is slid along the tubular portion 13, towardsthe connection flange 14, until a restraining ring 32 fixed firmly to orintegral with a side of the braking band 25 comes into contact with theinner abutment surface 28 of the set of teeth 26 of the bell 24.

[0052] The individual pieces 33 a, 33 b of the keeper ring 33 are thenplaced against the outer abutment surfaces 30, 31 of the engaged sets ofteeth 26, 27, from the exterior of the vehicle, and are connected to thebraking band 25 by screws 34 in order to restrain the braking bandaxially in the bell region 24 of the single body 2.

[0053] The wheel-support unit 1 for vehicles with disk brakes accordingto the invention has many advantages.

[0054] In the first place, it enables worn braking bands to be replacedwithout any operation on the bearing and with the use of one-piecebraking bands rather than the sectional braking bands of the prior art,resulting in low and uniform wear of the pads as well as a reduction incosts in comparison with braking bands of the prior art.

[0055] The present invention also enables the various components to beoptimized independently of one another, both with regard to theconstruction material and with regard to their geometrical shapes. Forexample, the structural separation of the braking band from the bellenables the bell itself, that is, the single body, to be made of a moreexpensive and stronger material than the material of the braking band.The thickness of the single body can consequently also be limited incomparison with that of the bell of the prior art, achieving a reductionin weight and hence a saving in material.

[0056] The bolts 12 which connect the single body to the bearing are notstressed further during braking and the braking torque is transmitteddirectly to the connection flange 14.

[0057] The wheel-support unit 1 is very strong and has an optimaldistribution of forces when the vehicle is in operation and inparticular during heavy braking.

[0058] The operations to fit and replace the braking bands are quickerand therefore cheaper than those of the prior art and fitting is furtherfacilitated by the shapes of the connecting portion 8 and of the seat 20of the single body 2.

[0059] Naturally, variations and/or additions may be applied to theembodiment described and illustrated, without departing from the scopeof the invention.

[0060] For example, the connecting portion 8 and the seat 20 may haveone or more complementary surfaces 10, 19, 22 for achieving a formcoupling between the outer ring 5 of the bearing 3 and the single body2.

[0061] According to one embodiment, this form coupling can prevent orlimit a relative translational movement between the outer ring 5 of thebearing 3 and the single body 2 in a direction substantiallyperpendicular to the axis S.

[0062] According to this embodiment, the form coupling also prevents orlimits relative rotational movement about the axis S between the outerring 5 of the bearing 3 and the single body 2.

[0063] According to an alternative embodiment, the bearing 3 has asubstantially cylindrical overall shape which enables the single body 2to be fitted on the bearing 3 in any angular position during mounting.

[0064] Naturally, in order to satisfy contingent and specificrequirements, a person skilled in the art may apply to the wheel-supportunit for vehicles with disk brakes according to the present inventionfurther modifications and variations all of which, however, are includedwithin the scope of protection of the invention as defined by theappended claims.

What is claimed:
 1. A wheel support for providing a connection,rotatable about an axis, between a wheel of a vehicle which can bebraked by a disk brake and suspension means of the vehicle, the supportcomprising a bell suitable for supporting a braking band and aconnection flange suitable for supporting the vehicle wheel, wherein thebell and the connection flange are formed integrally, constituting asingle body which can be connected rotatably and releasably to thesuspension means.
 2. A wheel support according to claim 1 in which thesingle body can be connected releasably to a bearing keyed to thesuspension means.
 3. A wheel support according to claim 2 in which thesingle body can be connected releasably to the bearing by means of aplurality of bolts.
 4. A wheel support according to claim 3 in which thesingle body comprises a shoulder provided with a flat abutment surfacesubstantially perpendicular to its axis, the shoulder having a pluralityof through-holes which open in the abutment surface and are distributedin alignment with internally-threaded holes provided in a front surfaceof the bearing, the through-holes being able to house the plurality ofbolts.
 5. A wheel support according to claim 4 in which thethrough-holes are distributed at intervals around a circle having itscentre on the axis.
 6. A wheel support according to claim 4 or claim 5in which the single body has a substantially tubular portion the outersurface of which forms the bell and the inner surface of which forms aseat for the releasable connection to the bearing.
 7. A wheel supportaccording to claim 6 in which the connection flange is formed as asubstantially annular disk perpendicular to the axis and has a pluralityof holes for housing bolts for the releasable connection of the wheel.8. A wheel support according to claim 7 in which the holes house thebolts with interference.
 9. A wheel support according to claim 7 orclaim 8 in which the connection flange is formed on the end of thesingle body remote from the seat.
 10. A wheel support according to claim9 in which a substantially frustoconical connecting region is formedbetween the connection flange and the tubular portion.
 11. A wheelsupport according to claim 10 in which the connecting region has one ormore reinforcing ribs.
 12. A wheel support according to claim 6 in whichthe bell region of the single body is suitable for forming a releasableconnection with the braking band, by means of suitable restrainingmeans.
 13. A wheel support according to claim 12 in which therestraining means comprise a set of teeth formed around the outercircumference of the bell region suitable for engaging a correspondingset of teeth formed around the circumference of the central opening ofthe braking band in order to achieve a releasable connection between thesingle body and the braking band, fixing them for rotation togetherabout the axis.
 14. A wheel support according to claim 13 in which theset of teeth comprises abutment surfaces which, together withcorresponding abutment surfaces of the set of teeth of the braking band,are in abutment with one or more restraining rings for preventing axialsliding of the braking band, at least beyond the limits provided for bythe bell region of the single body.
 15. A wheel support according toclaim 6 in which the seat of the single body has a depth such that itcan at least partially house the bearing.
 16. A wheel support accordingto claim 1 in which the single body as a whole is shaped substantiallyas an axially symmetrical body of revolution.
 17. A wheel-support unitcomprising a wheel support according to claim 1 as well as a bearingcomprising an inner ring which can be fixed firmly to the suspensionmeans, and an outer ring associated rotatably with the inner ring andhaving a connecting portion to which the single body can be fixedremovably by means of the plurality of bolts.
 18. A wheel-support unitaccording to claim 17 in which the connecting portion of the bearing andthe seat of the single body have one or more respective complementarysurfaces.
 19. A wheel-support unit according to claim 18 in which atleast one of the one or more complementary surfaces achieves a formcoupling between the connecting portion of the bearing and the seat ofthe single body when the single body is in the mounted condition on thebearing.
 20. A wheel-support unit according to claim 19 in which theform coupling can restrain and/or limit a translational relativemovement between the bearing and the single body in a directionperpendicular to the axis.
 21. A wheel-support unit according to claim19 or claim 20 in which the form coupling can restrain and/or limit arotational relative movement between the outer ring of the bearing andthe single body, about the axis.
 22. A wheel-support unit according toclaim 18 in which the connecting portion of the outer ring comprises aflat front surface substantially perpendicular to the axis and at leastpartially complementary with the abutment surface of the single body,the front surface having a plurality of holes which open in the frontsurface and which are distributed so as to be aligned with thethrough-holes provided in the abutment surface of the single body, theholes being suitable for housing the plurality of bolts.
 23. Awheel-support unit according to claim 22 in which the holes in the frontsurface of the bearing are internally threaded.
 24. A wheel-support unitaccording to claim 22 or claim 23 in which the outer ring of the bearingcomprises a first substantially tubular portion and a secondsubstantially tubular portion which is radially enlarged in comparisonwith the first tubular portion and which constitutes the connectingportion.
 25. A wheel-support unit according to claim 24 in which theouter ring comprises a substantially frustoconical transition regionbetween the first substantially tubular portion and the connectingportion.
 26. A wheel-support unit according to any one of the precedingclaims in which the direction in which the seat of the single body isfitted on the connecting portion of the bearing coincides substantiallywith the axis.
 27. A wheel-support unit according to claim 26 in whichthe seat of the single body is formed by a substantially cylindricalcavity having a centring portion, the inside diameter of whichcorresponds substantially to the outside diameter of the connectingportion of the bearing.
 28. A wheel-support unit according to claim 27in which, in the mounted condition, the bell region is disposedsubstantially centrally relative to the axial extent of the bearing. 29.A wheel-support unit according to claim 17 in which the bearing as awhole is shaped as a substantially axially symmetrical body ofrevolution.
 30. A suspension for vehicles which can be braked by diskbrakes, comprising a wheel-support unit according to claim
 17. 31. Abearing suitable for use in a wheel-support unit according to claim 17.